Commit 98e51a22 authored by Suren Baghdasaryan's avatar Suren Baghdasaryan Committed by Andrew Morton
Browse files

mm: conditionally write-lock VMA in free_pgtables 

Normally free_pgtables needs to lock affected VMAs except for the case
when VMAs were isolated under VMA write-lock.  munmap() does just that,
isolating while holding appropriate locks and then downgrading mmap_lock
and dropping per-VMA locks before freeing page tables.  Add a parameter to
free_pgtables for such scenario.

Link: https://lkml.kernel.org/r/20230227173632.3292573-20-surenb@google.com


Signed-off-by: default avatarSuren Baghdasaryan <surenb@google.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent 73046fd0

mm/internal.h

+1 −1
Original line number Diff line number Diff line
@@ -105,7 +105,7 @@ void folio_activate(struct folio *folio); 


void free_pgtables(struct mmu_gather *tlb, struct maple_tree *mt,

		   struct vm_area_struct *start_vma, unsigned long floor,

		   unsigned long ceiling);

		   unsigned long ceiling, bool mm_wr_locked);

void pmd_install(struct mm_struct *mm, pmd_t *pmd, pgtable_t *pte);



struct zap_details;

mm/memory.c

+5 −1
Original line number Diff line number Diff line
@@ -362,7 +362,7 @@ void free_pgd_range(struct mmu_gather *tlb, 


void free_pgtables(struct mmu_gather *tlb, struct maple_tree *mt,

		   struct vm_area_struct *vma, unsigned long floor,

		   unsigned long ceiling)

		   unsigned long ceiling, bool mm_wr_locked)

{

	MA_STATE(mas, mt, vma->vm_end, vma->vm_end);
@@ -380,6 +380,8 @@ void free_pgtables(struct mmu_gather *tlb, struct maple_tree *mt, 
		 * Hide vma from rmap and truncate_pagecache before freeing

		 * pgtables

		 */

		if (mm_wr_locked)

			vma_start_write(vma);

		unlink_anon_vmas(vma);

		unlink_file_vma(vma);
@@ -394,6 +396,8 @@ void free_pgtables(struct mmu_gather *tlb, struct maple_tree *mt, 
			       && !is_vm_hugetlb_page(next)) {

				vma = next;

				next = mas_find(&mas, ceiling - 1);

				if (mm_wr_locked)

					vma_start_write(vma);

				unlink_anon_vmas(vma);

				unlink_file_vma(vma);

			}

mm/mmap.c

+3 −2
Original line number Diff line number Diff line
@@ -2167,7 +2167,8 @@ static void unmap_region(struct mm_struct *mm, struct maple_tree *mt, 
	update_hiwater_rss(mm);

	unmap_vmas(&tlb, mt, vma, start, end, mm_wr_locked);

	free_pgtables(&tlb, mt, vma, prev ? prev->vm_end : FIRST_USER_ADDRESS,

				 next ? next->vm_start : USER_PGTABLES_CEILING);

				 next ? next->vm_start : USER_PGTABLES_CEILING,

				 mm_wr_locked);

	tlb_finish_mmu(&tlb);

}
@@ -3064,7 +3065,7 @@ void exit_mmap(struct mm_struct *mm) 
	set_bit(MMF_OOM_SKIP, &mm->flags);

	mmap_write_lock(mm);

	free_pgtables(&tlb, &mm->mm_mt, vma, FIRST_USER_ADDRESS,

		      USER_PGTABLES_CEILING);

		      USER_PGTABLES_CEILING, true);

	tlb_finish_mmu(&tlb);



	/*